Implement complete file manager keyboard shortcuts and copy functionality

Core Features:
- Full Ctrl+C/X/V/Z keyboard shortcuts system for file operations
- Real SSH file copy functionality supporting both files and directories
- Smart filename conflict resolution with timestamp-based naming
- Enhanced UX with detailed toast feedback and operation status

Technical Improvements:
- Remove complex file existence checks to prevent SSH connection hanging
- Optimize cp command with -fpr flags for non-interactive execution
- 20-second timeout mechanism for quick error feedback
- Comprehensive error handling and logging system

Keyboard Shortcuts System:
- Ctrl+A: Select all files (fixed text selection conflicts)
- Ctrl+C: Copy files to clipboard
- Ctrl+X: Cut files to clipboard
- Ctrl+V: Paste files (supports both copy and move operations)
- Ctrl+Z: Undo operations (basic framework)
- Delete: Delete selected files
- F2: Rename files

User Experience Enhancements:
- Smart focus management ensuring shortcuts work properly
- Fixed multi-select right-click delete functionality
- Copy operations with auto-rename: file_copy_12345678.txt
- Detailed operation feedback and error messages

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/ui/main-axios.ts

@@ -1136,6 +1136,30 @@ export async function deleteSSHItem(
   }
 }
 
+export async function copySSHItem(
+  sessionId: string,
+  sourcePath: string,
+  targetDir: string,
+  hostId?: number,
+  userId?: string,
+): Promise<any> {
+  try {
+    const response = await fileManagerApi.post("/ssh/copyItem", {
+      sessionId,
+      sourcePath,
+      targetDir,
+      hostId,
+      userId,
+    }, {
+      timeout: 60000, // 60秒超时，因为文件复制可能需要更长时间
+    });
+    return response.data;
+  } catch (error) {
+    handleApiError(error, "copy SSH item");
+    throw error;
+  }
+}
+
 export async function renameSSHItem(
   sessionId: string,
   oldPath: string,